Empty dSYM file detected

I’m just switching to CMake from .jucer file. If I do a clean build, everything works fine. But the second time I run I get the following error:

empty dSYM file detected, dSYM was created with an executable with no debug info.

First time dSYM is 200 MB, then second run it’s 5 MB. Any idea why my dSYM is getting deleted?